The present invention relates to a molding die for a component of molding a magnetic tape cartridge case. In particular, the present invention relates to a magnetic tape cartridge in which an electronic part (e.g. an IC board) for storing information as to managing recorded contents apart from a recording magnetic tape is incorporated as the need arises. In addition, the present invention also relates to a molding die for molding a magnetic tape cartridge having a lid structure.
Heretofore, a magnetic tape cartridge disclosed in Japanese Patent Unexamined Publication No. Sho. 63-168889 is already known, in which cartridge an electronic part (hereinafter referred to as, for example, an IC board as the IC board is often employed) for storing information as to managing recorded contents apart from a recording magnetic tape is incorporated, so that signals are exchanged between a record reproducing apparatus (e.g., hardware such as a tape recorder) and the IC board via its contacts which are exposed outside.
In this case, a cartridge case is provided with openings for use in exposing to the outside the contacts of the IC board incorporated in the cartridge case. When the IC board is incorporated in the cartridge case, the contacts of the IC board shut the inside openings, whereby the contacts on the hardware side can be brought into contact with the contacts of the IC board from the outside.
The aforementioned IC board is incorporated in such a cartridge case only when it is required and not incorporated therein when it is not required. Therefore, the openings are left open when the IC board is not incorporated and this may cause the contacts on the hardware side to be stuck in the openings.
Consequently, a dummy board instead of the IC board is normally incorporated so as to shut the openings from the inside.
In a case where a dummy board is used, the dummy board needs to be newly prepared as a part though a cartridge case remains to be used as a common part and this results in increasing the number of parts and necessitating the work of incorporating the dummy board, thus causing an increase in the cost of production. This is a problem.
In addition to this, with the recent technological innovation in increasing the density of magnetic recording media, magnetic tape cartridges, video tape recorders (hereinafter called "VTRs") and the like are increasingly made compact. Consequently, VTRs tend to become frequently used outdoors for taking photographs of landscapes, persons and the like.
For the reason stated above, there has been put to practical use a magnetic tape cartridge having two to three pieces of lids for covering the whole surface and undersurface of a magnetic tape so as to protect the magnetic tape from dust in consideration of the use of such a magnetic tape cartridge outdoors.
A description will subsequently be given of a conventional magnetic tape cartridge with reference to the accompanying drawings.
As shown in a perspective assembly drawing of FIG. 1, a magnetic tape 114 is stretched over the front of a magnetic tape cartridge 113 and while the magnetic tape 114 is not used, it is covered with an outer lid 115, a top lid 116 and an inner lid 117.
FIGS. 2 and 3 show a perspective and a sectional view of the lid portion, respectively.
The outer lid 115 has an outer lid portion 115a for covering the front of the magnetic tape 114 stretched in an opening portion 120, and side plates 115b for covering the front sides of an upper and a lower half 118, 119. The side plates 115b have a pair of fulcrum pins 115c, which are respectively inserted in a pair of notched portions provided in both front side portions of the upper half 118. The outer lid 115 is set rotatable around the fulcrum pins 115c. Further, a pair of pin holes 115d are made in the upper fronts of the side plates of the outer lid 115.
The top lid 116 has a top lid portion 116a for covering the upper edge of the magnetic tape 114 stretched in the opening portion 120, and side plates 116b for covering the side faces of the upper half 118. A pair of support pins 116c are provided on the side plates 116b of the top lid 116 and rotatably inserted into the pin holes 115d of the outer lid 115.
A pair of thin-wall portions that have been made as thin as the side plates 116b are provided on the respective front side faces of the upper half 118. Further, a pair of grooves for guiding the top lid are formed in the respective thin wall portions, and a pair of guide pins 116d formed on the rear insides of the side plates 116b are slidably mounted in the respective grooves.
A pair of bracket portions 116e are provided on the inside of the top lid 116, and pin holes 116f are formed in the respective bracket portions 116e.
FIG. 4 is a perspective view of the inner lid 117.
The inner lid 117 has an inner lid portion 117a for covering the undersurface of the magnetic tape 114 stretched in the opening portion 120, and side plates 117b. A pair of support pins 117c are provided on the respective side plates 117b of the inner lid 117 and rotatably inserted into the respective pin holes 116f of the bracket portions 116e of the top lid 116. Further, the lower side faces of the inner lid 117 are equipped with a pair of protrusions 117d, which are formed with guide pins 117e, respectively.
A pair of inner lid guide grooves whose top portions are opened are provided in the rear of a pair of tape guides formed in the lower half 119 and both side faces of the opening portion 120, and the pair of guide pins 117e formed on the protrusions 117d of the inner lid 117 are slidably inserted into the inner lid guide grooves.
A process for molding the inner lid 117 thus structured will subsequently be described. As shown in FIG. 5, a cavity 121 for use in molding the inner lid 117 includes a movable metal mold unit 122 and a stationary metal mold unit 123.
The movable metal mold unit 122 and the stationary metal mold unit 123 are placed opposite to each other so that mold breaking and clamping can be carried out by the locking unit of a molding machine, and in such a state that both of them have been clamped together, the cavity is formed. When the cavity 121 is filled with molten resin under pressure by an injection molding machine in such a clamped state before the molten resin is cooled and solidified, the inner lid 117 is formable.
Magnetic tape cartridges are classified into two categories; namely, for general use and for business use and those in both categories are similar in construction except that the inner lids for use in the former are longitudinally shorter than those for use in the latter. When these two kinds of inner lids are manufactured, however, the inner-lid molding method that has conventionally been adopted comprises the steps of preparing a special die for each type and setting the special die in a molding machine in agreement with the type of manufacture. In the molding method like this, troublesome work of removing the molding die from the molding machine, disassembling and assembling the die, mounting the die in the molding machine and so on has to be repeated in order each time the type of manufacture is changed, thus causing the rate of operation to be extremely lowered. Moreover, the cost of equipment tends to increase because kinds of dies to be prepared also increases, which results in incurring an increase in the cost of production. This is also a problem.